@type t() :: %LettaAPI.Model.IdentityUpsert{
  agent_ids: [String.t()] | nil,
  block_ids: [String.t()] | nil,
  identifier_key: String.t(),
  identity_type: LettaAPI.Model.IdentityType.t(),
  name: String.t(),
  project_id: String.t() | nil,
  properties: [LettaAPI.Model.IdentityProperty.t()] | nil
}